Run-to-run process control of oxide CMP using integrated metrology

Process control of dielectric CMP has become more stringent as device dimensions decrease. This study reports on the improvement in process control that was obtained by using an integrated metrology tool, and automated, factory-level, process control algorithms. The control methodology was proven to be capable of handling multiple pattern levels, with different pattern densities, on multiple polishers in an advanced-prototype/development fab. The improvement in controland throughput with respect to offline metrology and manual control is presented. Residual sources of variation are analyzed, and schema for further improvements in control capability are presented, based on tests conducted.